Generally, when mapping an engine on a dynamometer, coolant and oil temperatures must be regulated to specific setpoints. To achieve such specific setpoints, a heater and heat exchanger are employed to heat and cool parallel liquid flows. These flows are subsequently combined using a mixing valve to achieve a desired setpoint.
In most systems of this type, the heater and mixing valve are used at different times. Specifically, the heater is controlled to raise the temperature when the actual temperature is below the setpoint, and the mixing valve is controlled in other situations when the actual temperature is above the setpoint. Accordingly, the heater is used for temperature increases and the valve for temperature decreases. However, such systems can suffer from slow setpoint response, ineffective calibration and, ultimately, inaccurate temperature regulation. Accordingly, there is a need for systems and methods that achieve accurate temperature regulation and fast dynamic response. There is also a need for improved methods of control and/or assessing control authority of actuators of a powertrain system.